SOS!!!!, Brother-in-law needs help
stephan at psych.ucla.edu
Fri Oct 11 05:27:23 EST 1996
In article <53k62l$2si at news-e2d.gnn.com>, crs873 at gnn.com (Charles Snyder)
> My brother in law has come down with some type of strange neorological
> disorder. Last Wednesday (3/20/96) He awoke with a slight fever and a severe
> loss of both long-term and short-term memory. My sister took him to the
> hospital in Indy, the Neurologist there could find no clear cause. His
> symtoms include: short term memory loss, a sense of confusion between
> dreaming and waking states, at first a slight increase in his systolic blood
> pressure. His long term memory seems better now, but he still is confused
> about short term memory. The neorologist in Indy ordered CAT scans and MRIs
> and could find nothing abnormal. The nurses at the hospital mentioned
> something about this maybe a new virius. I also heard the very end of a
> story relating to some new virius with a odd name that I cannot remember, on
> Canadian Radio's "As It Happens", I do not know if these are related. The
> doctors did ask if he had recently been to California or the west coast.
> If any one has any information please Email me back. I do not know anymore
> details at this time. If you have some concerns or need further questions
> leave me a message and I will get you in contact with my sister. Thank you
> for your help!!!
> Charles Snyder Bedford, KY
Hmm. There is certainly an encephalitic virus that can produce similar
symptoms to this. The virus produces severe damage to the hippocampus
and surrounding medial temporal structures, and its effects are easy to see
on an MRI, and has previously occured in small epidemics. But there are
many more likely causes for these kinds of symptoms. However,
if you can provide a more clear description of the memory deficit, you
might be able to decide if there is probable hippocampal damage, since
even small lesions in this region can produce memory deficits.
1) you use the term "short-term memory" however, this term is often
used improperly, so I will give you a definition to work with:
STM is a store which holds about 7-9 items and, without rehearsal,
lasts about 3 minutes (but decays over that period). This is typically
the store where you would keep a phone number someone just told you,
and you can lengthen the time it lasts with rehearsal (repeating back
to yourself), but this will is easily disrupted by small distractions.
A standard test is a "digit span" test. Another standard test is
to ask someone to repeat items back to them, etc. Patients with restricted
hippocampal damage do not usually have any deficit on this task.
For the most part, it is associated with diffuse brain dmaage, and patients
with severe STM deficits can't even hold a conversation, because they
can't remember what you just said to them. Luckily, hippocampal patients
dont have a problem with this.
2) A hippocampal patient would pass #1 but if asked about the items
a few minutes later would not remember them. If the damage is severe,
he might not remember anything (like HM), or he might just do very
poorly. For the most part, severe patients are "frozen in time" such
that they don't put anything new into long-term memory from the time
of the insult to the brain. Oddly, their old long-term memories are
for the most part in tact. There is a variable "retrograde amnesia,"
where memories for events that occured prior to the trauma are lost,
but with hippocampal damage it is usually mild, i.e., 1-2 years prior
to the trauma, with childhood memories certainly in tact.
3) Lastly, this kind of memory syndrome can be caused by a transient
loss of blood/oxygen supply to the brain, and may not be associated
with any damage. Your brother would recover, but forever remain with
a poor memory for events around the time the ischemia/anoxia occured.
This is often seen in athletes with injuries, but usually doesn't
have any long-term consequences. The symptoms at first look just
like a hippocampal lesion, but go away after a highly variable amount of time.
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